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LAN & WLAN
Case Studies
How to configure a router
Original Polish version by Lukasz Sawicki
Proper configuration of the router is the precondition for networking and Internet access. Let's begin with the description of its functions. In general, router is a network device that is a communication node between the sending and receiving endpoint. The control of the traffic is called routing. Router creates a routing table or routing information base (RIB) that stores the best routes to certain network destinations, or the "routing metrics" associated with those routes, and the path to the next hop router. It allows to direct the packets to specified destinations. The routing process means interaction of at least two subnets.

The immense growth of the number of Internet users is the reason of remedial measures that overcome the limits of Ipv4 (Internet Protocol version 4). One of the measures is routing. It means linking of internal network with a pool of "private" IP addresses to the public network. Simply the router uses less (external) IP addresses than the number of supported computers in the local network. The diagram below depicts the typical solution.
Example of routing with NAT function
Router configuration example is based on the
TP-Link TL-WR340G device
Notice: TP-Link TL-WR340G N2952 does not support ADSL service (it is not equipped with ADSL modem).
Router connects two or more logical subnets, e.g. external network with Internet access (WAN) with local network (LAN), making a bridge for information exchange. Without proper configuration the connection would be impossible. In most cases, router acts as a specialized computer (replacing a standard computer) working in external network, with software and hardware tailored to the tasks of routing and forwarding. It allows to create internal (local) network.
In this case, the computer configuration involves:
  • taking down all settings of the NIC (working in external network),
    • IP address
    • Subnet mask
    • Default gateway
    • Preferred DNS server
  • changing the way of address assignment to dynamic (DHCP), or setting fixed IP address from the router's range,
  • connecting the computer with LAN port of the router.
Example of assigning a fixed IP address for TCP/IP protocol. This option is used when the router does not assign addresses automatically. At this stage there is no need to enter default gateway nor DNS servers parameters.
After restarting the computer, there is possibility of connecting with the router (via Internet browser). The logged in user (the initial user name and password are given in the user's manual) can configure the router.
The login window
The easiest way of configuring the router is use of "Quick Setup" option.
The first dialog box
To begin configuration we should choose Next.
It is important to select adequate kind of WAN connection type:
There are three possibilities:
  • PPPoE - in the case of network using PPPoE protocol (rather untypical),
  • Dynamic IP - the router will get IP address automatically (the most common option),
  • Static IP - in the case of fixed IP address.
Choice of WAN connection type
For Static IP option there are needed the settings of the NIC (to be entered). In the case of Dynamic IP this box will be omitted:

After configuring WAN port parameters the next step is setup of Access Point:
Planning to use access point, it is needed:
  • to select suitable channel,
  • to set SSID,
  • to choose the region (country),
  • to set data encryption and cryptographic keys (in the tab Wireless >> Wireless Settings).

Access Point setup box
It is important to choose adequate region:
Region selection box

Information on successful completion
It should be remembered that the addresses of the internal LAN have to be different from that of the WAN port (the same address would cause instability e.g. auto-reset of the router). For example, with IP address of WAN 192.168.1.1, the LAN network can be addressed 192.168.(not 1).1, or in quite different range, e.g. 150.10.0.1.
To set LAN parameters we enter Network >> LAN:

LAN address setup
Some ISPs identify the user by the MAC address of the NIC. To keep it unchanged (after exchanging the NIC port for the router's port) we use MAC Clone option (Network >> MAC Clone):

MAC Clone option
In the DHCP >> DHCP Settings box there is possibility of setting DHCP server parameters. With such configuration of the DHCP server the local computers can obtain their IP addresses automatically. It is a very convenient solution.

Example configuration of DHCP server
To ensure security of WiFi network it is needed to employ data encryption and assign cryptographic keys, in the Wireless >> Wireless Settings box.
Currently the best security level in home WLANs is provided by WPA2-PSK encryption (see below):

Advanced settings of Access Point
It is indispensable to change the default passwords in the administrator panel (System Tools >> Password). On the Internet there are active programs which try to log in to routers of the users that have forgotten to do so:

Change the default password !
In the Status window we may preview all the settings:
Status window
It is reasonable to save the configuration data:
System Tools >> Backup &Restore Configuration.
Backup &Restore Configuration box